The objective of this study was to evaluate the performance of the mesophilic and thermophilic anaerobic digestion process as an alternative for the biosolids production. Biological sludge from a municipal and industrial (brewery and pulp and paper) wastewater treatment plant using a UASB reactor was used. During the operation of the mesophilic batch system, the volatile solids (VS) were reduced from 60.3% (15.67 g/L) up to 37.5% (9.67 g/L) with 31 d of treatment time. The mesophilic process presented a stable operation reducing 38% of VS with 1.76 Kg VS m-3 d-1 of organic load feed fulfilling with the criterion of vectors attraction reduction. However, in mesophilic conditions, the digested sludge must be post-treated with a process of pathogenic microorganism inactivation because only remove low concentrations of pathogenic microorganism. The obtained results demonstrated that the process in thermophilic conditions (55°C) is capable to stabilize 3.9 Kg VS m-3 d-1 and to inactive the totality of fecal coliforms, Salmonella spp. and helminth ova fulfilling with the permissible limits for class A biosolids.